Reproduction

Pair formation begins as early as March. Pairs usually break-up shortly after the eggs are laid and incubation begins. The ducks are monogamous during the breeding season. They are not monogamous for life, however. Each season new pairs are formed. They engage in many courtship displays which include: head-shakes (the male simply shakes his head in the females direction), intro-shakes (the male, to gain the female's attention, treads water then rises above the water and shakes his head), grunt-whistles (the male places his bill in the water, pulls it up while making noise and splashes the water in the air), inciting (the female performs this display for the male after the pair has formed), preen-behind-wing (fake preening).

This whole display takes only about three minutes. The ducks also have another courtship ritual in which the male swims around the female, pulling his head in and out of the water; this behavior is known as bridling.

Mating System: monogamous

Mottled ducks breed once yearly. Eighty percent have formed pairs by November and mating begins in January. The nests are made of matted grass and are on the ground or suspended over shallow water and are in dense grasses. Females lay 5 to 13 eggs per clutch. The eggs take 24 to 28 days to hatch. The ducks fledge after 45 to 56 days. They are independent adults in 65 to 70 days. Both males and females are sexually mature in one year.

After the eggs hatch, the females lead the brood from the nest. The ducklings are precocial and are able to find their own food. They tend to eat invertebrate larvae when available. The mothers care for the young approximately 20% of the day. The mother spends 34% of her time feeding, 28% resting, 11% preening and 20% watching for predators. The females give alarm calls if an intruder approaches the nest or her young. Broods tend to gather together at night to keep safe. The females usually stay with the ducklings until they can fly (about 45 to 56 days).